Can you think of any three-dimensional shape that comprises of exactly two surfaces?

There is one thing that goes round the house and also inside the house but never even share a brief touch. What is it?

I am a prime number.
The double of myself is equal to the square of me.

which number am I?

The horse jumps over the king.
Strangely there is absolutely no scratch on him.

Can anyone explain, how is this possible?

The product of three consecutive numbers is 7980.
Then the sum of these consecutive numbers would be?

I am a white box having no key or lid.
Yet there is a golden treasure inside it.

What Am I?

There are people and strange monkeys on this island, and you can not tell who is who (Edit: until you understand what they said - see below). They speak either only the truth or only lies.
Who are the following two guys?
A: B is a lying monkey. I am human.
B: A is telling the truth.

While going to your grandmother's house, you counted Twenty houses on the right side. While returning back to your home, you counted Twenty houses on the left side.

How many houses are there between your home and your grandmother's home?

You have four chains. Each chain has three links in it. Although it is difficult to cut the links, you wish to make a single loop with all 12 links. What is the fewest number of cuts you must make to accomplish this task?

It's a test that will check your IQ.

Suppose you have one 11 minute hourglass and one 13 minute hourglass.

Can you measure exactly fifteen minutes using them ?